[ovs-dev] [idl 1/2] ovsdb-idl: Fix atomicity of writes that don't change a column's value.

Andrew Evans aevans at nicira.com
Fri Apr 8 17:25:26 UTC 2011


On 4/5/11 12:24 PM, Ben Pfaff wrote:
> +    /* If this is a write-only column and the datum being written is the same
> +     * as the one already there, just skip the update entirely.  This is worth
> +     * optimizing because we have a lot of columns that get periodically
> +     * refreshed into the database but don't actually change that often.
> +     *
> +     * We don't do this for read/write columns because that would break
> +     * atomicity of transactions--some other client might have written a
> +     * different value in that column since we read it. */

What prevents another client from writing a different value since we
last read the row?



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